Strictly speaking, I suspect the glamorgan sausage ought to fall into that much-maligned category of what evangelical omnivores like to term "fake meat", being both sausage-shaped and sausage-monikered, but not actually containing any dead animals. Yet it doesn't seem to attract the same level of outrage as other vegetarian alternatives – perhaps because it's so unquestionably delicious. I suppose it's hard to feel vitriolic with crumbs round your mouth.

The glamorgan sausage first pops up in print in the wonderfully Victorian travelogue, Wild Wales: Its People, Language and Scenery, but despite Wales' long reputation for fine meat, the recipe seems likely to be much older; as early as the 12th century, the chronicler Gerald of Wales remarked on the country's dependence on dairy produce.

A product of necessity, rather than vegetarian principle, the glamorgan sausage apparently experienced a revival in popularity when meat rationing came into force, though I could find no wartime recipes to try, much to my disappointment. Happily, I wasn't short of more modern alternatives.

The cheese

Canteen's glamorgan sausages. Felicity Cloake/Guardian

Traditionally, one assumes the glamorgan sausage would have been made using the local cheese, which, given just one herd of the chestnut-coloured glamorgan cow remains, is sadly no longer in production. As it was a crumbly white variety, most recipes suggest substituting caerphilly, which is apparently similar in texture and taste, but Jane Grigson gives the option of lancashire in English Food, while the Hairy Bikers recommend Welsh cheddar as an alternative. (The happily vague recipe from Croeso Cymreig, a book of Welsh recipes published by the Wales Gas Board in the 1950s, just calls for cheese – probably appropriately in a recipe originally designed to make the best of scarce resources.) Welsh cheddar, which I find more easily than caerphilly, is unmistakably cheesy – not a bad thing, certainly, but the more lactic creaminess of caerphilly is a subtler pleasure. Lancashire, which crumbles in a similar way, gives the sausages a slightly saltier, less rounded flavour, but will do if you can't get hold of any caerphilly.

The bread

Croeso Cymreig's glamorgan sausages. Felicity Cloake/Guardian

Breadcrumbs are the thrifty bulking agent of the sausage. There is little variation, though Bobby Freeman, a chef and the author of various books on Welsh cookery, writes in First Catch Your Peacock: "I like to make glamorgan sausages with half white and half brown breadcrumbs." I agree; the white crumbs are fluffier while the brown add a more savoury flavour, but in the spirit of the dish, I'd advise using whatever you have to hand. Interestingly, the recipe book from the London restaurant chain Canteen, Great British Food, uses a mixture of boiled potatoes and breadcrumbs. Spuds put in an appearance in mass-produced glamorgan sausages, but this is the only recipe I find that uses them, and I'm not keen at all: it makes them more like a rather heavy croquette. (Plus, as Croeso Cymreig notes, the only proper way to serve glamorgan sausages is "with creamed potatoes or chips".)

The liquid

Hairy Bikers' glamorgan sausages. Felicity Cloake/Guardian

Egg is the best way to bring the mixture together; most recipes use the yolks as binding, and keep the whites for the coating. Nigel Godwin, writing in the Telegraph, uses the whole egg mixed with mustard. I find it better to separate them, so the yolk adds richness to the sausage, but stirring the mustard into the yolks does make it easier to distribute evenly. He also adds some milk, making his mixture wetter than the rest and very slightly harder to shape (nothing that can't be solved by half an hour in the fridge), but also softer and less stodgy than many competitors, some of which tend towards the heavy.

The flavourings

Jane Grigson's glamorgan sausages. Felicity Cloake/Guardian

Cheese, of course, cries out for onion. You could use the real thing, as Croeso Cymreig and Matthew Fort suggest, or spring onions, as Grigson does, but Wales' beloved leek seems more appropriate. And, much as I love the gloriously unsubtle kick of cheese and onion, the combination of sweet leeks and sour, creamy caerphilly is a more interesting one. Godwin sticks his leeks in raw, but this means they're still rather crunchy in the finished product; softening them in butter, as the Bikers and Canteen recommend, is a worthwhile use of time.

Thyme and parsley are the most popular herb choice; Canteen uses sage, which is frankly weird, and Croeso Cymreig's pinch of dried mixed herbs make the sausages taste too much like 1957 for comfort. After eating a few versions, I decide the parsley's not pulling its weight: pretty as the green flecks look, I can't taste them, so I decide to cut it out. Fiercely aromatic thyme needs no backup in any case. One thing I am going to steal from Canteen's recipe is their pinch of nutmeg; a good friend to both cheese and leeks, it's an inspired addition. Mustard is ubiquitous, as in the welsh rarebit, and the kick of English suits my taste better than Godwin's vinegary Dijon here.

Coating and cooking

Nigel Godwin's glamorgan sausages. Felicity Cloake/Guardian

Most recipes fry them, with the Abergavenny Food Festival's Country Table recommending deep-frying "for a crisper coat and a softer inside". I give this a try, and it is good – but, surprisingly, so is Riverford Farm's baked recipe. In fact, a spell in the oven may not deliver the crispest coating, but it does render the interior hotter and gooier than the shallow-fried versions. It does leave the crumb a bit dry, though, so I'm going to combine the two: frying them briefly, then finishing them off in the oven (though it's no disaster if you can only be bothered to either bake or fry them).

Croeso Cymreig and Grigson cook their sausages in lard; hardly the ideal veggie option. The Bikers' vegetable oil works fine, but best of all is Godwin's butter. I like to think it's the traditional choice in dairy country.

Melt half the butter in a frying pan and sweat the leeks over a medium heat until well softened. Season well with salt, pepper and nutmeg.

Mix 100g breadcrumbs with the thyme, and beat the egg yolks and mustard together. Crumble the cheese into the breadcrumb mixture and stir in the leeks, followed by the egg yolks and mustard. Season, mix well and add the milk.

Shape into six sausages (damp hands will make this easier) and chill for half an hour.

Heat the oven to 180C/350F/gas mark four. Meanwhile, whisk the egg whites until frothy. Put the egg whites, flour and remaining breadcrumbs on separate plates, and roll each sausage in the flour, then whites, then breadcrumbs to coat.

Melt the remaining butter in the pan over a medium-high heat. When hot, add the sausages and cook until just golden on each side. Transfer to a baking sheet and cook for about 20 minutes, until richly golden. Serve immediately.

Glamorgan sausages: the best vegetarian sausages out there, or can you offer other contenders to the crown? And can anyone spread any more light on the history of this Welsh classic and its sadly lost cheese?